[bravejason]

When is a no trump bid the unusual no trump showing the two lower ranking unbid suits and when does it show a generic ‘two places to play’?

[pescetom]

A good place to start is Roth's original paper on Unusual NT. You can find it in .pdf format for free.

[helene_t]

Over 2♠ it is never unusual*. It can be two places to play.

Over 2♥ it is never just two places to play. It may be showing both minors.

Over 2♦ and 2♣ it is neither.

Over 1NT and lower it can be the two lower suits. Never just two places to play.

Of course there are also situations where it is Lebensohl, some other form of puppet or transfer to 3♣, or natural.

*Possible exception: some people play, against multi 2♦,
(2♦)-p-(2♥)-p
(2♠)-2NT**
** both minors because with hearts you would have bid 2♥ on the previous round.
Maybe similar against a Precision 1♦:
(1♦)-p-(1♠)-p
(2♠)-2NT**

[pescetom]

helene_t, on 2018-October-24, 15:17, said:

*Possible exception: some people play, against multi 2♦,
(2♦)-p-(2♥)-p
(2♠)-2NT**
** both minors because with hearts you would have bid 2♥ on the previous round.
Maybe similar against a Precision 1♦:
(1♦)-p-(1♠)-p
(2♠)-2NT**

We would play it as Unusual in both examples, but in the first because on the previous round we would have bid DBL with hearts or 2NT with 16-18 and a spades stopper.

[P_Marlowe]

The question is, do you have enough room or not.
If you have enough room, i.e. a complete level of bids, e.g. you are currently
at the 1 level, than you have the complete 2 level av., and espesially you are
able to bid their suit as some kind of cue ..., in this case, the cue showes
a 2-suiter, and 2NT can show a different 2-suiter, or you have agreed that a
2 level suit bid showes a 2-suiter (see defences to their NT opening).
If you dont have the space, than you have to put all 2-suiters in the 2 NT / 4NT bid.

[Tramticket]

helene_t, on 2018-October-24, 15:17, said:

Over 2♠ it is never unusual*. It can be two places to play.

Over 2♥ it is never just two places to play. It may be showing both minors.

Over 2♦ and 2♣ it is neither.

Over 1NT and lower it can be the two lower suits. Never just two places to play.

I've not really thought this through before and I don't think that we would ever play a low-level no trump bid as two places to play. Can you give some examples of a NT bid over 2♠ showing two places to play? For example a simple 2NT overcall of 2♠ would be natural for us (and for most?). I guess that a sequence such as Pass, (2♠), Pass, (Pass); 2NT cannot be natural, but we would be more likely to protect with a double in case partner has spade values and is looking for a penalty. In this case I would expect partner to hold both minors and respond on that assumption. I would understand if partner held hearts and diamonds and bid 2NT, intending to remove 3♣ and bid 3♦ (pass or correct), but I would not expect partner to hold a two-suiter in hearts and clubs (we would have to double).

[P_Marlowe]

Tramticket, on 2018-October-25, 05:05, said:

I've not really thought this through before and I don't think that we would ever play a low-level no trump bid as two places to play. Can you give some examples of a NT bid over 2♠ showing two places to play? For example a simple 2NT overcall of 2♠ would be natural for us (and for most?). I guess that a sequence such as Pass, (2♠), Pass, (Pass); 2NT cannot be natural, but we would be more likely to protect with a double in case partner has spade values and is looking for a penalty. In this case I would expect partner to hold both minors and respond on that assumption. I would understand if partner held hearts and diamonds and bid 2NT, intending to remove 3♣ and bid 3♦ (pass or correct), but I would not expect partner to hold a two-suiter in hearts and clubs (we would have to double).

#1 (1S) - Pass - (2S) - 2NT
#2 similar in reopening position, but not your given seq., with the weak 2S

[helene_t]

Tramticket, on 2018-October-25, 05:05, said:

I've not really thought this through before and I don't think that we would ever play a low-level no trump bid as two places to play. Can you give some examples of a NT bid over 2♠ showing two places to play? For example a simple 2NT overcall of 2♠ would be natural for us (and for most?). I guess that a sequence such as Pass, (2♠), Pass, (Pass); 2NT cannot be natural, but we would be more likely to protect with a double in case partner has spade values and is looking for a penalty. In this case I would expect partner to hold both minors and respond on that assumption. I would understand if partner held hearts and diamonds and bid 2NT, intending to remove 3♣ and bid 3♦ (pass or correct), but I would not expect partner to hold a two-suiter in hearts and clubs (we would have to double).

Yes, 2NT by a passed hand is an example, if you don't play Lucas/Muiderberg/Polish 2-openings. It is true you sometimes prefer double, but if you have hearts+clubs you don't want partner to bid diamonds in response to you double. And if you double and then correct 3♣ to 3♦, it sounds more like 4-6 than 5-5.

Also in response to partner's reopening double. For example,
1NT-(2♠)-p-(p)
dbl-(p)-2nt

Here, it is probably slightly more efficient to play 2NT as an unknown single suiter and play 3♣/♦ as the lower of two suits. But standard is to play 2NT as scrambling with two suits.

[Tramticket]

helene_t, on 2018-October-25, 15:58, said:

Also in response to partner's reopening double. For example,
1NT-(2♠)-p-(p)
dbl-(p)-2nt

Thanks Helene. Yes, I can see that.